Hey there, Kiki2.

Thanks for reaching out to us here in the Community. Guiding you to the right direction for adding a class on your bank data is my priority.

The batch option to change is currently unavailable in QuickBooks Desktop. When adding or modifying transaction classes, you’ll have to go through by line item and manually edit the information.

1. Go to Lists at the top menu bar, then select Chart of Accounts.
2. Choose the correct bank account, then double-click on the transaction to see the details.
3. Choose the Expenses tab.
4. In the Class column, click on the drop-down and select the correct category.
5. Click on Save & Close. 

You'll have to follow the same steps to change the class for each transaction. I'm adding screenshots to visually guide you:

The information I provided should help you moving forward.

If there’s anything else I can help you with, please let me know by posting a comment. I’m always ready to assist you further.